CN118234605A

CN118234605A - Method for producing a peripherally reinforced ceramic honeycomb body and extrusion die

Info

Publication number: CN118234605A
Application number: CN202280075568.2A
Authority: CN
Inventors: S·贝比; T·W·布鲁; R·R·加尔加利卡; P·P·哈里哈兰; K·C·吴; M·拉维钱德兰
Original assignee: Corning Inc
Current assignee: Corning Inc
Priority date: 2021-11-30
Filing date: 2022-11-17
Publication date: 2024-06-21
Also published as: WO2023101819A1

Abstract

An extrusion die (500) is provided having a die slot geometry corresponding to the matrix region (120), perimeter region (130), and rounded transition region (440) of the resulting honeycomb body (100), and a method of manufacturing a ceramic honeycomb article (100) having perimeter reinforcing features using such an extrusion die (500) is provided. A method (600) is described that includes extruding (620), drying, and firing (630) a green honeycomb body (100) formed by extruding a batch mixture through an extrusion die (500) having a die slot width and corner radii (R1, R2, R3) that vary over two or more regions (120, 130). The extrusion die (500) and method (600) of making the ceramic honeycomb article (100) address manufacturing and performance difficulties present in high porosity and ultra high porosity products.

Description

Method for producing a peripherally reinforced ceramic honeycomb body and extrusion die

Cross reference to related applications

The present application claims priority from U.S. patent application serial No. 63/284133 filed on date 2021, 11, 30, 35u.s.c. ≡119, the contents of which are hereby incorporated by reference in their entirety.

Technical Field

The present disclosure relates generally to ceramic honeycomb bodies, and more particularly, to extrusion dies and methods for making high porosity ceramic honeycomb bodies having perimeter reinforcing features.

Background

Ceramic honeycomb bodies are widely used in applications including filters and substrates in emission control systems for various types of vehicles. For example, when an engine of an automobile or other vehicle type burns fuel, diesel or gasoline, its exhaust gases carry harmful byproducts, such as hydrocarbons, oxynitrides, carbon monoxide and particulates. Ceramic honeycomb bodies may be incorporated as part of emission control systems associated with such vehicles to remove harmful gases and particulates from the vehicle exhaust.

In particular, ceramic honeycomb bodies having thousands of parallel channels may be formed into substrates or filters that may be used to repair gaseous contaminants or remove particulate contaminants, respectively. Using an extrusion process, ceramic honeycomb bodies for forming such substrates and filters can be produced from high temperature low expansion materials capable of withstanding high temperatures and rapid temperature changes. However, due to the thin walls, high porosity and the process used, the honeycomb must have sufficient green strength for handling during manufacturing and isostatic strength after firing for operational use.

Thus, it is desirable to improve the manufacturability and strength of high porosity ceramic honeycombs.

Disclosure of Invention

The present disclosure provides extrusion dies and methods of using extrusion dies to make ceramic honeycomb bodies. In particular, extrusion dies for forming ceramic honeycombs with high perimeter reinforcing features are described herein, as well as methods of using such extrusion dies.

According to an embodiment, an extrusion die configured to extrude a ceramic honeycomb body is provided. The extrusion die head includes: a plurality of feed holes extending from the inlet face into the die body, the plurality of feed holes configured to receive batch materials; and a plurality of die slots extending from the discharge face into the die body and connected to the plurality of feed holes, wherein each die slot of the plurality of die slots is configured to discharge batch material as a green honeycomb body; wherein a first portion of the plurality of die slots corresponds to a matrix region of the extrusion die, a second portion of the plurality of die slots corresponds to an inner peripheral region of the extrusion die, and a third portion of the plurality of die slots corresponds to an outer peripheral region of the extrusion die; wherein the die slots in the matrix region have a first width, the die slots in the inner peripheral region have a second width, and the die slots in the outer peripheral region have a third width, wherein the second width is greater than the first and third widths.

In an embodiment, the width of the die slot in the second portion increases from the first width to the second width in increments.

In embodiments, the delta is about 0.1 mil to about 1.0 mil.

In an embodiment, the first width is less than about 5.0 mils and the second width is greater than about 7.0 mils.

In an embodiment, the width of the die slot in the third section decreases in an incremental manner (INCREMENTALLY) from the second width.

In an embodiment, each die slot of the plurality of die slots has a fillet radius that increases from a first fillet radius in a matrix region of the extrusion die to a second fillet radius in at least one of an inner perimeter region of the extrusion die and an outer perimeter region of the extrusion die.

In an embodiment, the first width of the die slot in the matrix region of the extrusion die is less than about 5.0 mils.

In an embodiment, the die slots in the matrix region of the extrusion die have a constant die slot width.

In an embodiment, the fillet radii of the plurality of die slots increase from a first fillet radius to a second fillet radius in variable fillet increments.

In an embodiment, the variable fillet increment is about 0.1 mil to about 1.0 mil.

In an embodiment, a method of making a ceramic honeycomb article is provided. The method comprises the following steps: extruding the batch mixture through a plurality of die slots of an extrusion die to form a green ceramic honeycomb body having a plurality of cell channels formed by intersecting cell walls; and drying and firing the green ceramic honeycomb body to form a ceramic honeycomb article; wherein the green ceramic honeycomb body comprises: a matrix region comprising a first portion of the plurality of cell channels formed by intersecting cell walls, the intersecting cell walls having a first web thickness; an inner peripheral region comprising a second portion of the plurality of cell channels formed by intersecting cell walls having a second web thickness; and an outer peripheral region comprising a third portion of the plurality of cell channels formed by intersecting cell walls having a third web thickness, wherein the second web thickness is greater than the first web thickness and the third web thickness.

In an embodiment, the intersecting cell walls forming the second portion of the plurality of cell channels in the inner peripheral region increase in mesh increments from a first mesh thickness to a second mesh thickness.

In embodiments, the web delta is about 0.1 mil to about 1.0 mil.

In an embodiment, the web thickness is variable.

In an embodiment, the first web thickness is less than about 5.0 mils and the second web thickness is greater than about 7.0 mils.

In an embodiment, the thickness of the intersecting cell walls forming the third section of the plurality of cell channels in the peripheral region decreases in web increments from the second web thickness.

In an embodiment, the cross-cell walls forming the plurality of cell channels have a fillet radius, and wherein the fillet radius of the cross-cell walls increases from a first fillet radius in the matrix area to a second fillet radius in at least one of the inner perimeter area and the outer perimeter area in variable fillet increments.

In an embodiment, the intersecting cell walls of the green ceramic honeycomb body have a minimum corner radius of about 2.0 mils and a maximum corner radius of about 4.4 mils.

In an embodiment, the green ceramic honeycomb body has a variable fillet radius-to-web thickness (FTW) ratio of from about 0.1 to about 1.5.

In an embodiment, a ceramic honeycomb article manufactured according to the method of any of the preceding paragraphs is provided.

Drawings

In the drawings, like reference numerals generally refer to the same parts throughout the different views. Moreover, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of various embodiments.

Fig. 1 is an elevational view of a ceramic honeycomb body showing a first end, a plurality of cell channels formed by intersecting inner walls, and an outer perimeter wall according to the present disclosure.

Fig. 2A is an elevation view of a ceramic honeycomb body, revealing an inner matrix region according to the present disclosure.

Fig. 2B is an elevation view of a ceramic honeycomb body, exhibiting a reinforced perimeter region surrounding an inner matrix region in accordance with the present disclosure.

Fig. 2C is an elevation view of a ceramic honeycomb body, revealing an inner perimeter region in accordance with the present disclosure.

Fig. 2D is an elevation view of a ceramic honeycomb body, revealing an outer perimeter region in accordance with the present disclosure.

Fig. 3 is an enlarged schematic top view of a ceramic honeycomb body showing a plurality of cells with rounded corners formed by intersecting cell walls in accordance with the present disclosure.

FIG. 4 is an enlarged elevation view of a portion of a ceramic honeycomb body showing a plurality of cell channels in a matrix region, a perimeter region, and a rounded transition region.

Fig. 5 is a schematic partial cross-sectional view of a ceramic batch material being extruded through an extrusion die incorporating perimeter-strengthening features in accordance with the present disclosure.

FIG. 6 is a flow chart illustrating a method of manufacturing a ceramic honeycomb body having perimeter reinforcement features in accordance with the present disclosure.

Figures 7A and 7B graphically illustrate extrusion die slot width transitions over the perimeter regions of two different extrusion dies in accordance with the present disclosure.

Fig. 8 is a modeling graph of cell wall stress as a function of cell wall thickness in accordance with the present disclosure.

Fig. 9 is a graph comparing the ratio of fillet radius to cell wall thickness over the transition perimeter regions of three ceramic honeycombs.

Detailed Description

The present disclosure provides apparatus and methods for manufacturing ceramic honeycomb bodies having perimeter-strengthening features. More specifically, the apparatus includes an extrusion die designed to impart corresponding perimeter-reinforcing features to a ceramic honeycomb body having a plurality of microscopic channels formed by very thin walls and a high surface area.

As exhaust emissions regulations become more stringent, the design of exhaust components such as ceramic honeycombs tends to reduce the cell density and reduce the web thickness to provide lower pressure drop and faster catalyst light-off response (e.g., in the case of catalyst-containing substrates). For example, ultra-high porosity honeycombs with large surface areas and/or high catalyst volumes are one of the product designs that have the potential to meet future ultra-low NO _x regulations. However, these thin-walled, high porosity ceramic honeycombs result in an overall weaker structure and reduced mechanical durability, making them more difficult to withstand the mechanical and thermal stresses of the exhaust system environment. In addition, these ceramic honeycombs are difficult to process and handle subsequently because they are prone to cracking, chipping, cracking, and have flow defects. The extrusion die and extrusion apparatus described herein address and solve many of these problems.

Turning to fig. 1, an elevation view of a ceramic honeycomb body 100 according to the present disclosure is shown, comprising: a first end 102, a plurality of porthole passages 104 formed by intersecting inner walls 106, and an outer peripheral skin or wall 108. The ceramic honeycomb body 100 may also include a second end 110 positioned opposite the first end 102. In particular embodiments, the plurality of cells 104 and the intersecting cell walls 106 may extend between the first end 102 and the second end 110 of the honeycomb body 100. The plurality of tunnel passages 104 may be configured to allow for the flow of a fluid (e.g., exhaust from an exhaust system of an associated vehicle). For example, the plurality of porthole channels 104 may be a plurality of continuous, uninterrupted, parallel fluid conducting portholes oriented along an axis from the first end 102 to the second end 110. The first end 102 may be an inlet face that receives a fluid flow into the cell channels 104 of the honeycomb body 100; while the second end 110 may be the discharge face where the fluid flow exits the cell channels 104 of the honeycomb body 100. Thus, in some embodiments, the plurality of porthole channels 104 are not plugged and thus provide unimpeded fluid flow from the first end 102 to the second end 110. In alternative embodiments, at least a portion of the plurality of cell channels 104 may be plugged to force the fluid stream to flow through the porous ceramic material of the walls 106, thereby arranging the ceramic honeycomb body 100 as a particulate filter or a wall-flow filter.

Turning to fig. 2A-D and as further disclosed herein, the ceramic honeycomb 100 of the present disclosure may include: an inner matrix area 120, a perimeter area 130 surrounding the inner matrix area 120, and an outer skin (i.e., outer wall) 108 surrounding both the perimeter area 130 and the matrix area 120. As shown in fig. 2C and 2D, the perimeter region 130 may include an inner perimeter region 132 and an outer perimeter region 134. In an embodiment, the matrix region 120 includes a first portion of the plurality of channels 104, the inner perimeter region 132 includes a second portion of the plurality of channels 104, and the outer perimeter region 134 includes a third portion of the plurality of channels 104. A first portion of the plurality of channels 104 may be defined as intersecting cell walls 106 in the matrix region 120, while second and third portions of the plurality of channels 104 may be defined as intersecting cell walls 106 in the inner and outer peripheral regions 132 and 134, respectively.

In other embodiments, the plurality of porthole channels 104 may contain a catalyst that facilitates a chemical reaction that converts one or more undesirable compounds (e.g., CO, NO _x, and hydrocarbons) to pollution-free compounds (e.g., H ₂O、O₂ and N ₂). For example, in some embodiments, at least a portion of the plurality of porthole channels 104 comprises a catalyst coating deposited on a surface thereof (i.e., the intersecting porthole walls 106 forming the at least a portion of the plurality of porthole channels 104 are coated with a catalyst material). In other embodiments, at least a portion of the porous ceramic material forming the intersecting cell walls 106 of one or more of the plurality of cell channels 104 is impregnated with a catalyst material. The catalyst may include, for example, but is not limited to: noble metals (e.g., platinum, rhodium, palladium), alumina or other catalyst materials, and combinations thereof.

Ceramic honeycomb body 100 may be formed by extruding the batch mixture through an extrusion die of an extrusion apparatus, as described below. For example, the batch mixture used to form ceramic honeycomb body 100 may include one or more inorganic ceramic or ceramic precursor particles, such as: alumina, silica, titania, magnesia, clay, talc, cordierite, mullite, silicon carbide, aluminum titanate, and combinations thereof. The batch mixture may additionally contain, among other additives or ingredients: a liquid carrier (e.g., water), an organic binder (e.g., methylcellulose), a pore former (e.g., starch, polymer particles, or graphite), and a lubricant (e.g., oil or fatty acid), thereby affecting the final properties of the ceramic honeycomb body 100 and/or aiding in one or more manufacturing steps.

The ceramic honeycomb 100 of the present disclosure may be a high porosity honeycomb, e.g., having an overall porosity of at least about 50%, at least 55%, or even at least about 60%, e.g., about 60% to about 70%, and combinations of any of the endpoints thereof.

In other embodiments, the porosity of matrix region 120 may be different or the same as the porosity of perimeter region 130. For example, the porosity of the matrix region 120 may be greater than, may be less than, or may be equal to the porosity of the perimeter region 130. In particular embodiments, the porosity of matrix region 120 and the porosity of perimeter region 130 may independently be about 60% to about 70%, and combinations of any of its endpoints.

Although not limited to a particular geometry, the honeycomb body 100 may be cylindrical with a cylindrical matrix region 120 having a diameter (D) of about 4 inches to about 13 inches, including about 4 inches to about 8 inches and about 8 inches to about 13 inches. Further, the peripheral region 130 may be cylindrical and the inner and outer peripheral regions 132, 134 may have widths W ₁ and W ₂, respectively, such that the peripheral region 130 has a width (W) of about 0.2 inches to about 1.5 inches, including about 0.2 inches to about 0.5 inches and about 0.5 inches to about 1.5 inches. In particular embodiments, the diameter (D) of the matrix region 120 may be about 12 inches and the width (W) of the perimeter region 130 may be about 0.85 inches. In other embodiments, the outer skin 108 may be cylindrical and have a thickness of about 5 mils to about 50 mils.

Further, while not limited to a particular geometry, the cross-cell walls 106 may have a thickness (which may be referred to as web thickness or wall thickness) of about 2 mils to about 9 mils, including: about 2 mils to about 4 mils, about 4 mils to about 6 mils, about 6 mils to about 9 mils, and any combination of endpoints thereof. In an embodiment, the thickness of the wall 106 in the matrix region 120 is different from the thickness of the wall 106 in the perimeter region 130. In an embodiment, the web thickness of the intersecting cell walls 106 in the matrix region 120 is less than about 6 mils, including less than about 5 mils. In an embodiment, the web thickness of the cross-cell walls 106 in the perimeter region 130 is greater than the thickness of the walls 106 in the matrix region, such as greater than 5 mils, including greater than about 6 mils, greater than about 7 mils, and greater than about 8 mils. In particular embodiments, the web thickness of the cross-cell walls 106 in the matrix region 120 is less than the web thickness of the cross-cell walls 106 in the perimeter region 130. At least some of the walls in the inner peripheral region 132 may be the maximum thickness of all of the walls in the ceramic honeycomb body 100, as described herein. Thus, the maximum thickness of the walls in the inner perimeter region 132 may be greater than the maximum thickness of the walls of either the matrix region 120 or the outer perimeter region 134.

According to other aspects of the present disclosure, the web thickness of the cross-cell walls 106 may be a constant thickness or may have a variable web thickness. Specifically, the matrix region may include a plurality of cell channels 104 formed by intersecting cell walls 106 having a first web thickness, the inner perimeter region 132 may include a plurality of cell channels 104 formed by intersecting cell walls 106 having a web thickness that increases from a second web thickness to a third web thickness, and the outer perimeter region 134 may include a plurality of cell channels 104 formed by intersecting cell walls 106 having a web thickness that decreases from a fourth web thickness to a fifth web thickness. For example, the web thickness of the intersecting cell walls 106 in the inner perimeter region 132 may be increased as it moves away from the matrix region 120 and toward the outer skin 108.

In some aspects, the increase in web thickness of the intersecting cell walls 106 in the inner peripheral region 132 may be the same amount between each set of adjacent cell channels 104 or may increase at a variable increment/rate. For example, the web thickness of the cross-cell wall 106 in the inner perimeter region 132 may be increased from the second web thickness to the third web thickness at a variable web increment/rate of about 0.1 mil to about 1.0 mil, including: about 0.1 mil, about 0.2 mil, about 0.3 mil, about 0.4 mil, about 0.5 mil, about 0.6 mil, about 0.7 mil, about 0.8 mil, about 0.9 mil, and about 1.0 mil. More specifically, the cross-cell walls 106 in the inner peripheral region 132 may have a variable web delta/rate with a minimum value of at least about 0.3 mils and a maximum value of at least about 0.8 mils. In other aspects, the intersecting cell walls 106 in the inner peripheral region 132 may remain constant at a third web thickness for one or more pairs of adjacent cell channels 104, as shown in fig. 7B.

In other aspects, the reduction in web thickness of the intersecting cell walls 106 in the outer peripheral region 134 may be the same amount between each set of adjacent cell channels 104 or may be reduced at a variable increment/rate. For example, the web thickness of the cross-cell walls 106 in the outer peripheral region 134 may be reduced at a variable web increment/rate of about 0.1 mil to about 1.0 mil, including: about 0.1 mil, about 0.2 mil, about 0.3 mil, about 0.4 mil, about 0.5 mil, about 0.6 mil, about 0.7 mil, about 0.8 mil, about 0.9 mil, and about 1.0 mil. In other aspects, the intersecting cell walls 106 in the outer peripheral region 134 may remain constant at a fifth web thickness for one or more pairs of adjacent cell channels 104, as shown in fig. 7B.

Referring now to fig. 3, an enlarged view of a portion of a ceramic honeycomb body 300 according to other aspects of the present disclosure is shown. In particular embodiments, one or more of the plurality of porthole channels (e.g., porthole channel 104) may be rounded or not. For example, referring to fig. 3, the cell channels 304A are not rounded, while the cell channels 304B, 304C, and 304D are rounded to varying degrees. Each of the rounded cell channels 304B, 304C, 304D may have a rounded radius, which means that the roundness of the channels 304B, 304C, 304D is rounded. As shown, the cell channels 304B have a fillet radius R ₁, the cell channels 304C have a fillet radius R ₂, and the cell channels 304D have a fillet radius R ₃, where R ₁>R₂>R₃. By increasing the corner radius, there is the effect of decreasing the area of the channels 304B, 304C, 304D and increasing the cell wall thickness 305B, 305C, 305D around the corners of the channels 304B, 304C, 304D. In particular embodiments, the fillet radius (e.g., radius R ₁、R₂、R₃) may be about 2.0 mils to about 4.4 mils, as well as any combination of endpoints thereof.

Furthermore, the corner radii of the ceramic honeycomb body 100 disclosed herein may be independently selected. For example, the ceramic honeycomb bodies described herein may include rounded transition regions wherein the corner radii of the plurality of cell channels vary between one or more adjacent cell channels. Referring specifically to fig. 4, an enlarged portion of a honeycomb body 400 is shown comprising a plurality of cell channels 404 formed by intersecting cell walls 406. As discussed above, the honeycomb body 400 may include: a matrix region 420 including a first portion of the plurality of porthole channels 404, and a perimeter region 430 having an inner perimeter region and an outer perimeter region including second and third portions of the plurality of porthole channels 404. As shown, the honeycomb body 400 may also include a rounded transition region 440. In aspects, the rounded transition region 440 may overlap a portion of the matrix region 420 and the perimeter region 430, such as an inner perimeter region or inner and outer perimeter regions. In other words, the rounded transition region 440 may include a portion of the matrix region 420 and a portion of the perimeter region 430. Thus, portions of the rounded transition region 440 may have a constant web thickness and/or a variable web thickness, as discussed above.

More specifically, in the fillet transition 440, the fillet radii of the intersecting cell walls 406 forming the plurality of cell channels 404 may transition from a first fillet radius in the matrix area to a second fillet radius in at least one of the inner and outer peripheral areas. In an aspect, the corner radius of the cross-cell walls 406 increases from a first corner radius to a second corner radius in variable corner increments. For example, the first fillet radius may be about 2.0 mils, the second fillet radius may be about 4.4 mils, and the fillet radii of the intersecting cell walls 406 forming the plurality of cell channels 404 transition from 2.0 mils to 4.4 mils in incremental steps (INCREMENTAL STEP) in the fillet transition area 440. In some embodiments, the corner radius of the cross-cell walls 406 in the corner transition region 440 may transition from the first corner radius to the second corner radius at about 0.2 mils, about 0.3 mils, about 0.4 mils, about 0.5 mils, about 0.6 mils, about 0.7 mils, about 0.8 mils, about 0.9 mils, about 1.0 mils.

According to other aspects of the present disclosure, the matrix region 420 and the perimeter region 430 of the ceramic honeycomb body 400 may have defined fillet-to-web thickness (FTW) ratios. In particular embodiments, the FTW ratio of matrix area 420 may be about 0.5 to about 1.5. In particular embodiments, the maximum FTW ratio in the matrix area is no more than about 1.5, including no more than about 1.25 and no more than about 1. In other embodiments, the FTW ratio of the perimeter region 430 may also be about 0.5 to about 1.5. In particular embodiments, the maximum FTW ratio in the perimeter region 430 is no more than about 1.5, including no more than about 1.25 and no more than about 1. Further, as discussed below with reference to fig. 9, the maximum difference in FTW ratio between any two adjacent porthole channels 404 is less than or equal to about 0.25, including less than about 0.25, less than about 0.2, less than about 0.15, and less than about 0.1. In particular embodiments, the FTW ratio does not change (i.e., is uniform) in certain regions of the honeycomb (e.g., matrix regions), while the FTW ratio changes in other regions of the honeycomb (e.g., perimeter region(s) and/or rounded transition regions).

In addition, the ceramic honeycomb 400 of the present disclosure may have a stress magnification factor that indicates a lower propensity for cracking of the honeycomb 400 during firing. For example, in particular embodiments, the honeycomb 400 may have a stress magnification factor of up to about 1.75, including: about 1.75, about 1.74, about 1.73, about 1.72, about 1.71, about 1.7, about 1.69, about 1.68, about 1.67, about 1.66, about 1.65, about 1.64, about 1.63, about 1.62, about 1.61, about 1.6, about 1.59, about 1.58, about 1.57, about 1.56, about 1.55, about 1.54, about 1.53, about 1.52, about 1.51, about 1.5, about 1.49, about 1.48, about 1.47, about 1.46, about 1.45, about 1.44, about 1.43, about 1.42, about 1.41, about 1.4, about 1.39, about 1.38 about 1.37, about 1.36, about 1.35, about 1.34, about 1.33, about 1.32, about 1.31, about 1.3, about 1.29, about 1.28, about 1.27, about 1.26, about 1.25, about 1.24, about 1.23, about 1.22, about 1.21, about 1.2, about 1.19, about 1.18, about 1.17, about 1.16, about 1.15, about 1.14, about 1.13, about 1.12, about 1.11, about 1.1, about 1.09, about 1.08, about 1.07, about 1.06, about 1.05, about 1.04, about 1.03, about 1.02, about 1.01, about 1, and the ranges formed by such endpoints. As used herein, the term stress-amplifying factor refers to the ratio of the maximum vertical stress in the fillet area to the maximum vertical stress in the web.

The firing behavior of examples 3,4 and 5 are shown as respective stress magnification factors, as shown in table 3. Example 3, with a step change in corner radius, exhibited the stress riser and thus had the highest stress magnification factor, while examples 4 and 5 exhibited lower stress magnification factors and thus would have a lower propensity for cracking. As used herein, the term stress-amplifying factor refers to the ratio of the maximum vertical stress in the fillet area to the maximum vertical stress in the web. Thus, a lower stress magnification factor indicates a lower propensity for cracking during firing.

Turning now to fig. 5, a cross-section of an extrusion die 500 configured to extrude a ceramic honeycomb body (e.g., honeycomb body 100) having perimeter-strengthening features is shown in accordance with the present disclosure. Extrusion die 500 includes a die body 512 provided with feed holes 514 extending from an inlet face 510 into die body 512, thereby introducing batch material 516 into die body 512. In other words, the inlet face 510 may be configured to receive batch material 516 via the plurality of feed holes 514. Coupled to feed aperture 514 are a plurality of die slots 518, 519 which terminate at an exit face 520 of die body 512, whereby batch material 516 is extruded into the form of green honeycomb extrudate 530. The extruded green honeycomb body 530 may include an outer extruded skin 536 surrounding the body 530 and the intersecting cell walls 532. For example, the honeycomb extrudate 530 may be cut to length to form the honeycomb body 100.

As described above, the honeycomb extrudate 530 may include: a matrix region having thin intersecting cell walls 532 with a first maximum web thickness; near the inner perimeter region, having intersecting cell walls 533 with a second maximum web thickness; and an outer peripheral region having cross-cell walls 534 with a third maximum web thickness, wherein the second maximum web thickness of wall 533 is greater than the first and second web thicknesses of cross-cell walls 532, 534 in the matrix region and in the outer peripheral region, respectively. In an embodiment, the third maximum web thickness is wider than the first maximum web thickness. The honeycomb extrudate 530 may also include a rounded transition region that overlaps at least a portion of the matrix region and the perimeter region, as described herein.

Thus, extrusion die 500 includes: a corresponding matrix region of narrow die slots 517 having a first slot width (corresponding to the first web thickness); an inner peripheral region of die slot 518 having a second slot width (corresponding to the second web thickness); and an outer peripheral region of die slot 519 comprising a third slot width (corresponding to the third web thickness), wherein the second slot width is the widest slot width in die 500 (which correspondingly results in the second web thickness of wall 533 in the inner peripheral region also being widest). As such, porthole channels 538 in each of the matrix region, inner perimeter region, outer perimeter region, and/or rounded transition region may correspond to one or more portions of the plurality of die slots 518, 519.

More specifically, extrusion die 500 may include a plurality of die slots, wherein a first portion of the plurality of die slots corresponds to a matrix region of extrusion die 500, a second portion of the plurality of die slots corresponds to an inner peripheral region of extrusion die 500, and a third portion of the plurality of die slots corresponds to an outer peripheral region of extrusion die 500.

In aspects, the honeycomb extrudate 530 may comprise about 600 cell channels 538 per square inch of honeycomb body. In some embodiments, the honeycomb body 530 may be cylindrical and may include multiple layers of adjacent cell channels 538 corresponding to the layers of adjacent die slots 517, 518, 519 of the extrusion die 500. For example, the peripheral region (i.e., inner and outer peripheral regions) of the honeycomb body 530 may comprise about 5 to about 50 (e.g., about 10 to about 20) layers of adjacent cell channels 538 (although only some are shown in fig. 5 for clarity), and the portions of the plurality of die slots 517, 518, 519 corresponding to this region may correspondingly comprise about 5 to about 50 (e.g., about 10 to about 20) layers of adjacent die slots. Similarly, the rounded transition region of honeycomb 530 may comprise about 2 to about 6 layers of adjacent cell channels 538, and the portion of the plurality of die slots 517, 518, 519 corresponding to this region may comprise about 2 to about 6 layers of adjacent die slots.

Further, each die slot 517, 518, 519 may be defined by a die slot width and a corner radius. When the fillet radius is 0, the channel has a perpendicular (square) angle. Thus, a first portion of the plurality of die slots 517 corresponding to the matrix region of extrusion die 500 may have at least a first die slot width, a second portion of the plurality of die slots 518 corresponding to the inner peripheral region of extrusion die 500 may have at least a second die slot width, and a third portion of the plurality of die slots 519 corresponding to the outer peripheral region of extrusion die 500 may have at least a third die slot width. Similarly, each of the plurality of die slots 518, 519 may have a fillet radius that increases from a first fillet radius in the matrix region of the extrusion die 500 to a second fillet radius in at least one of the inner perimeter region and/or the outer perimeter region of the extrusion die 500.

According to other aspects of the present disclosure, die slot widths and/or corner radii may vary between die slots in different regions and/or may vary between die slots in the same region. For example, in each of the matrix, perimeter, and rounded transition regions, the corresponding die slots may have maximum and minimum die slot widths that vary between two or more adjacent die slots and maximum and minimum corner radii that vary between two or more adjacent die slots. In some embodiments, portions of the die slots 517, 518, 519 corresponding to one or more regions described herein may also include a mid-width and/or a mid-fillet radius. For example, slots 518 in the inner perimeter region may be stepped incrementally from a first slot width up to a second slot width of slots 517 in the matrix region. In other words, each region described herein may comprise a plurality of different widths. Thus, unless otherwise specified, reference herein to a first groove width, a second groove width, a third groove width, a first web thickness, a second web thickness, or a third web thickness generally refers to the maximum value of the relevant width or thickness.

In embodiments, the variation in die slot width or width delta between any two adjacent die slots 517, 518, 519 may be from about 0.1 mil to about 1.0 mil. In embodiments, the variation in fillet radius or fillet radius delta between any two adjacent die slots 517, 518, 519 may be from about 0.2 mils to about 1.0 mils. In certain embodiments, the width of the die slots 518, 519 may be from about 4.0 mils to about 8.2 mils, as well as combinations of any of its endpoints.

In an embodiment, the width of die slots 517 corresponding to the matrix areas is less than or equal to about 4.0 mils. In other embodiments, as described above, the width of the die slots 518, 519 corresponding to the perimeter region(s) may increase at a variable rate (or increment) as one moves from the matrix region toward the outer skin 536. For example, the width of die slot 518 closest to the matrix region may be approximately 4 mils, which then increases by at least 0.4 mils between adjacent tunnel channels 538. In some embodiments, the width of die slot 518 may be increased until it reaches a maximum die slot width proximate to the boundary or transition between the inner and outer peripheral regions. For example, the width of die slot 518 may be increased until it reaches a maximum die slot width of 8 mils or greater. The width of die slots 519 in the outer peripheral region may be reduced to one or more intermediate die slot widths between the inner peripheral region and outer skin 536. For example, the width of the die slot 519 corresponding to the outer perimeter region may decrease from a maximum in the inner perimeter region to an intermediate die slot width of about 7 mils or less.

Further, as described above, the honeycomb extrudate 530 may include a rounded transition zone (e.g., rounded transition zone 440). Thus, extrusion die 500 may have die slots 517, 518, 519 configured to extrude intersecting cell walls 532, 533, 534 having rounded corners of different fillet radii. More specifically, extrusion die 500 may include: die 500 corresponds to one or more die slots 517 in a portion of the matrix area of honeycomb extrudate 530; die 500 corresponds to one or more die slots 518 in the portion of honeycomb extrudate 530 near the inner perimeter region; and one or more die slots 519 corresponding to an outer peripheral region of the honeycomb extrudate 530.

Referring to fig. 6, a method 600 of manufacturing a ceramic honeycomb article having perimeter reinforcing features is also provided herein. The method 600 begins at step 610. At step 620, method 600 includes extruding the batch mixture through a plurality of die slots of an extrusion die to form a green ceramic honeycomb (i.e., a wet or unfired ceramic honeycomb structure). The green ceramic honeycomb body may comprise: a plurality of cell channels formed by intersecting cell walls, and an outer skin surrounding the plurality of cell channels. The green ceramic honeycomb body may further comprise: an inner matrix region comprising a first portion of the plurality of porthole channels; an inner peripheral region comprising a second portion of the plurality of porthole channels; and an outer peripheral region comprising a third portion of the plurality of porthole channels.

At step 630, the method 600 includes drying and firing the green ceramic honeycomb body to form a dried ceramic honeycomb body as known in the art. According to various aspects of the present disclosure, die slots corresponding to the matrix region, the inner perimeter region, the outer perimeter region, and the optional rounded transition region of the extrusion die may be practiced as discussed above. That is, the die slots of the extrusion die may be configured to extrude the batch material such that the dried honeycomb body comprises a matrix region, an inner peripheral region, an outer peripheral region, and a rounded transition region, as described herein.

In particular embodiments, method 600 further includes step 640, wherein the dried honeycomb body is contoured (contour) to form a ceramic honeycomb article. More specifically, step 640 includes removing one or more outer channels from a peripheral region of the dried ceramic honeycomb body to form a ceramic honeycomb article. For example, in some embodiments the walls and channels corresponding to the outer perimeter may be removed, such that the resulting honeycomb after the removal process contains only matrix regions and inner perimeter regions. If the outer peripheral region of the honeycomb body is removed, an adhesive or other material may be applied to the remaining honeycomb structure to form the outer skin 108. Optionally, the method 600 may also include plugging one or more cell channels of the dried honeycomb body to form a filter, or subjecting to catalyst washcoating to impregnate the walls of the cells with catalyst, as mentioned above. Thus, the ceramic honeycomb article may be, for example, but is not limited to, a filter or substrate for an exhaust gas emission system, including a catalytic converter substrate.

Examples

Referring to fig. 7A and 7B, two extrusion die designs are schematically shown. The portions of the extrusion die represented in the figures shown in fig. 7A and 7B correspond to the peripheral regions of the ceramic honeycomb body. That is, the extrusion die is shown forming part of the peripheral region of the ceramic honeycomb body in accordance with certain aspects of the present disclosure. As shown, both the first and second embodiments include a plurality of die slots corresponding to the tunnel channels of the peripheral region. In a first embodiment, the die slot width is shown to increase from a minimum die slot width to a maximum die slot width, which then maintains a plurality of channeled die slots. In a second embodiment, the die slot width is shown to increase from a minimum die slot width to a maximum die slot width and then decrease to an intermediate die slot width, which then maintains a plurality of channel-forming die slots. However, in both embodiments, the increment between adjacent channeled slots is initially small, but is increased between each subsequent adjacent cell pair. Table 1 below shows the specific die slot widths and increments (Δ) for two examples:

TABLE 1

Further, as shown in table 1, the peripheral region of the honeycomb body had about 20 adjacent cell channels, which corresponds to individual die slots of varying width.

Referring to fig. 8, a modeling plot of web stress as a function of web thickness in a perimeter region is shown, showing that web stress decreases as web thickness in the perimeter region increases. Specifically, fig. 8 shows that a web thickness of about 7.1 mils in the peripheral region of the honeycomb is the optimal thickness for achieving the strength required to avoid causing defects in the article due to handling.

Referring to fig. 9, three embodiments of a transition between a matrix region of a honeycomb body and a perimeter region of the honeycomb body are illustratively shown with the Y-axis showing the ratio of fillet radius to web thickness (i.e., FTW ratio). As shown, examples 4 and 5 have a gradual transition of FTW ratio between their respective matrix and perimeter regions, while example 3 has a large change in FTW ratio (corresponding to a sudden increase in fillet radius). Tables 2 and 3 below show the corner radii and resulting properties of these three examples, respectively.

TABLE 2

TABLE 3 Table 3

The firing behavior of examples 3,4 and 5 are shown as respective stress magnification factors, as shown in table 3. Example 3, with a step change in corner radius, exhibited the stress riser and thus had the highest stress magnification factor, while examples 4 and 5 exhibited lower stress magnification factors and thus would have a lower propensity for cracking. As described above, the term stress-amplifying factor refers to the ratio of the maximum vertical stress in the fillet area to the maximum vertical stress in the web. Thus, a lower stress magnification factor indicates a lower propensity for cracking during firing.

In accordance with these and other aspects of the present disclosure, the extrusion dies and ceramic honeycombs described herein address the manufacturing and performance difficulties presented by ultra high porosity products, significantly reduce the risk of defects in the shaping and firing process steps required to manufacture the final ceramic honeycomb products, reduce the time required to manufacture the extrusion dies by more than 33%, and improve differential flow in extrusion.

It will be understood that all definitions defined and used herein take precedence over dictionary definitions of defined terms, definitions in documents incorporated by reference, and/or general meanings.

As used herein in the specification and claims, the indefinite articles "a" and "an" are to be understood as meaning "at least one" unless explicitly stated to the contrary.

As used herein, the phrase "and/or" as used in the specification and claims should be understood to mean "either or both" of the associated elements, i.e., elements that in some cases have relevance and in other cases have no relevance. A plurality of elements listed as "and/or" should be read in the same manner, i.e. "one or more" such combined elements. Through the "and/or" term, other elements may optionally be present in addition to the specifically named elements, whether or not they are related or unrelated to those elements specifically named.

As used herein in the specification and in the claims, "or" should be understood to have the same meaning as "and/or" as defined above. For example, when items are listed separately, "or" and/or "should be read as inclusive, i.e., including at least one, but also including more than one, of the listed elements and, optionally, additional unlisted items. Only the use of the contrary terms such as "wherein only one" or "exactly one" or in the claims, "consisting of" is intended to mean that the inclusion of a plurality of elements or exactly one of the listed elements. In general, the term "or" as used herein should be read to indicate an exclusive substitution (i.e., "one or the other but not both") only when preceded by an exclusive term (e.g., "either," "one of," "only one of," or "exactly one").

As used herein in the specification and in the claims, the phrase "at least one" in reference to a listed element or elements should be understood to mean that at least one element is selected from any one or more of the listed elements, but does not necessarily include each and at least one of each of the specifically listed elements, and does not exclude any combination of elements from the listed elements. This definition also allows that elements other than the specifically named element of the list of elements to which the phrase "at least one" refers may optionally be present, whether or not they relate to those elements specifically named or not.

It should also be understood that, in any method claimed herein that protects more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order of the steps or acts of the method as set forth unless clearly indicated to the contrary.

It is to be understood that in the claims and the above description, all transitional phrases such as: "including," "comprising," "carrying," "having," "containing," "involving," "holding," and "including" are open ended, meaning including, but not limited to. Only the transitional phrases "consisting of" and "consisting essentially of" will be closed or semi-closed transitional phrases, respectively.

The subject matter described above is that the above embodiments may be implemented in any number of ways. For example, some aspects may be performed in hardware, software, or a combination thereof. When any aspect is performed at least in part in software, the software code may be executed on any suitable processor or collection of processors, whether provided in a single device or computer or distributed among multiple devices/computers.

Although various examples have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the functions and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the examples described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific examples described herein. It is, therefore, to be understood that the foregoing examples are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the examples may be practiced otherwise than as specifically described and claimed. Examples of the present disclosure relate to each individual feature, system, article, material, and/or method described herein. Moreover, any combination of two or more such features, systems, articles, materials, and/or methods, if such features, systems, articles, materials, and/or methods are not mutually inconsistent, is included within the scope of the present disclosure.

Claims

1. An extrusion die configured to extrude a ceramic honeycomb body, the extrusion die having a die body comprising:

a plurality of feed holes extending from the inlet face into the die body, the plurality of feed holes configured to receive batch materials; and

A plurality of die slots extending from the discharge face into the die body and connected to the plurality of feed holes, wherein each die slot of the plurality of die slots is configured to discharge batch material as a green honeycomb body;

wherein a first portion of the plurality of die slots corresponds to a matrix region of the extrusion die, a second portion of the plurality of die slots corresponds to an inner peripheral region of the extrusion die, and a third portion of the plurality of die slots corresponds to an outer peripheral region of the extrusion die;

Wherein the die slots in the matrix region have a first width, the die slots in the inner peripheral region have a second width, and the die slots in the outer peripheral region have a third width, wherein the second width is greater than the first and third widths.

2. The extrusion die of claim 1, wherein the width of the die slot in the second section increases from the first width to the second width in increments.

3. The extrusion die of claim 2, wherein the delta is about 0.1 mil to about 1.0 mil.

4. The extrusion die of claim 1, wherein the first width is less than about 5.0 mils and the second width is greater than about 7.0 mils.

5. The extrusion die of claim 1, wherein the width of the die slot in the third section decreases incrementally from the second width.

6. The extrusion die of claim 1, wherein each die slot of the plurality of die slots has a fillet radius that increases from a first fillet radius in a matrix region of the extrusion die to a second fillet radius in at least one of an inner perimeter region of the extrusion die and an outer perimeter region of the extrusion die.

7. The extrusion die of claim 6, wherein the fillet radii of the plurality of die slots increase from a first fillet radius to a second fillet radius in variable fillet increments.

8. The extrusion die of claim 7, wherein the variable fillet increment is about 0.1 mil to about 1.0 mil.

9. The extrusion die of claim 1, wherein the first width of the die slots in the matrix region of the extrusion die is less than about 5.0 mils.

10. The extrusion die of claim 1, wherein the die slots in the matrix region of the extrusion die have a constant die slot width.

11. A method of making a ceramic honeycomb article, the method comprising:

Extruding the batch mixture through a plurality of die slots of an extrusion die to form a green ceramic honeycomb body having a plurality of cell channels formed by intersecting cell walls; and

Drying and firing the green ceramic honeycomb body to form a ceramic honeycomb article;

Wherein the green ceramic honeycomb body comprises:

A matrix region comprising a first portion of the plurality of cell channels formed by intersecting cell walls, the intersecting cell walls having a first web thickness;

An inner peripheral region comprising a second portion of the plurality of cell channels formed by intersecting cell walls having a second web thickness; and

An outer peripheral region comprising a third portion of the plurality of cell channels formed by intersecting cell walls having a third web thickness, wherein the second web thickness is greater than the first web thickness and the third web thickness.

12. The method of claim 11, wherein the intersecting cell walls forming the second portion of the plurality of cell channels in the inner peripheral region increase in web increments from a first web thickness to a second web thickness.

13. The method of claim 12, wherein the web delta is about 0.1 mil to about 1.0 mil.

14. The method of claim 11, wherein the web increment is variable.

15. The method of claim 11, wherein the first web thickness is less than about 5.0 mils and the second web thickness is greater than about 7.0 mils.

16. The method of claim 11, wherein the thickness of the intersecting cell walls forming the third portion of the plurality of cell channels in the peripheral region decreases in web increments from the second web thickness.

17. The method of claim 11, wherein the intersecting cell walls forming the plurality of cell channels have a fillet radius, and wherein the fillet radius of the intersecting cell walls increases from a first fillet radius in the matrix area to a second fillet radius in at least one of the inner peripheral area and the outer peripheral area in variable fillet increments.

18. The method of claim 17 wherein the intersecting cell walls of the green ceramic honeycomb body have a minimum fillet radius of about 2.0 mils and a maximum fillet radius of about 4.4 mils.

19. The method of claim 11, wherein the green ceramic honeycomb body has a variable fillet radius-web thickness (FTW) ratio of about 0.1 to about 1.5.

20. A ceramic honeycomb article made by the method of claim 11.